多裂纹介质在动态载荷作用下的断裂特性研究  

Study on Fracture Property in Multi-crack Medium under Dynamic Loading

作　　者：李清[1] 郭洋[1] 董明明[1] 王思嘉[1] 周泽建[1] 

机构地区：[1]中国矿业大学(北京)力学与建筑工程学院,北京100083

出　　处：《科学技术与工程》2016年第19期6-10,36,共6页Science Technology and Engineering

基　　金：国家自然科学基金(51374212;51134025)资助

摘　　要：采用含双平行裂纹的半圆盘有机玻璃模型,以落锤作为动态加载装置,对动态载荷下多裂纹介质的断裂行为进行了研究。研究结果表明:在动载作用下,含多裂纹的脆性材料的应力场与单一裂纹时的应力场有明显不同。多裂纹介质中裂纹尖端的应力场多为拉剪混合应力场,裂纹起裂多为I-II混合型裂纹,但当裂纹扩展以后,裂纹逐渐向拉伸破坏转变;在多裂纹介质中,当已有一条裂纹扩展时,邻近平行裂纹尖端的能量被释放,邻近平行裂纹尖端的应力集中程度也逐渐下降,说明扩展裂纹对相邻平行裂纹的起裂和扩展有一定的抑制作用;在动载作用下,多裂纹介质中裂纹的起裂韧度KI由2.86 MN/m2下降到1.95 MN/m2,说明多裂纹对介质的起裂韧度有影响。但当试件中有一条裂纹扩展后,邻近平行裂纹对扩展裂纹的传播韧度和扩展速度的影响逐渐减弱。A series of experiments were conducted on polymethylmethacrylate（ PMMA） using semi-circular bending specimen containing multi-cracks to study dynamic fracture behaviors of multi-cracks medium under impact loading.The results show that： under dynamic loading,the stress field of brittle material containing multi-cracks was different from the stress field of brittle material containing single crack.The stress field around crack tips in multi-cracks medium was always tension-shear stress field,the crack initiation was mode I-II,but when the cracks propagated,the cracks appeared tension failure; in multi-cracks medium,when a crack propagated,the energy of the neighbor crack would release,stress concentration decreased,which means cracks propagation prevented the initiation and propagation of the neighbor crack; under dynamic loading,the initiation fracture toughness in multicracks medium decreased from 2.86 MN/m2 to 1.95 MN/m2,which showed that multi-cracks affected initiation fracture toughness,however,when a crack propagated,the neighbor crack could not affect the initiation fracture toughness and crack velocity.

关 键 词：动态荷载 多裂纹介质 焦散线方法 应力强度因子 裂纹扩展速度 

分 类 号：O346.11[理学—固体力学]